Pump Device for Ice Cream or Yogurt Machine

ABSTRACT

A system includes a pump device for producing a mixture product, a casing having a concealed cavity for receiving the mixture product via the pump device; and a clutch unit operatively linked to the pump device for controllably maintaining an interior pressure of the concealed cavity at a predetermined threshold. Accordingly, the pump device is activated by the clutch unit for delivering the mixture product into the concealed cavity through an inlet of the casing until the interior pressure of the concealed cavity reaches the predetermined threshold and is deactivated by the clutch unit for stop delivering the mixture product into the concealed cavity when the interior pressure of the concealed cavity reaches the predetermined threshold.

CROSS REFERENCE OF RELATED APPLICATION

This is a Continuation-In-Part application that claims the benefit ofpriority under 35 U.S.C. §119 to a non-provisional application,application Ser. No. 12/932,580, filed Feb. 28, 2011.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a pump device, and more particularly toa pump device for a yogurt or ice-cream machine which is capable ofpreventing mixture leakage while allowing convenient cleaning of thepump device.

2. Description of Related Arts

A conventional pump for feeding liquid mixture for ice-cream or yogurtusually comprises a casing having a liquid inlet, an air inlet and amixture outlet, and a plurality of intermeshing rotors, received in thecasing to connect the liquid inlet, the air inlet and the mixtureoutlet. In particular, the intermeshing rotors are connected with eachother to define a first chamber and a second chamber such that when oneof the intermeshing rotors is rotated, another intermeshing rotor isdriven to rotate to create a suction effect from the first chamber tothe second chamber.

Conventionally, liquid and air enter the pump through the liquid inletand air inlet respectively into the first chamber, wherein the liquidand air mix in the pump to form mixture which is then pumped out of thesecond chamber to feed an ice-cream or yogurt machine for makingice-cream or yogurt. There are several disadvantages regarding thisconventional pump.

First, the rotors of the conventional pump are usually gears which mustintermesh with each other in a very precise manner for facilitatingeffective mixing of liquid and air and for accomplishing efficientoperation of the pump. As a result, each of the components of the pump,and especially the rotors, must be made very precise in order to alloweach of the components to fit with each other for creating a suctioneffect between the first and second chambers and for effectively andefficiently making ice-cream or yogurt. All these requirements accountfor the very expensive manufacturing cost and their ultimate sellingprice of conventional pumps for ice-cream and yogurt machines.

Second, since the components of the conventional pumps must be veryprecise, it is very difficult for users of conventional pumps todisassemble and reassemble the pump for cleaning. As a matter of fact,since the pump is primarily used for pumping liquid having a relativelyhigh viscosity, it needs cleaning regularly. However, the pump isusually mounted adjacent to the ice-cream or yogurt machine and shouldbe connected to a tank or storage device for storing the liquid. Theresult is that it is very difficult for a user to detach the pump fromother devices (such as the ice-cream machine) for cleaning. Likewise, itis very difficult or at least very inconvenient for the user toreassemble the pump and reattach it with other machines or devices.

Furthermore, when the components of the pump are made to be veryprecise, it is very difficult for users of the pump to reassemble thepump with the same precision as tough the pump was not disassembled.When the pump is not reassembled properly, the performance of the pumpwill be deteriorated and this in turn affects the quality or theefficiency of the ice-cream or yogurt produced.

In addition, since the casing is made of stainless steel, theintermeshing rotors must be made of different materials such as alloy.Accordingly, in order to provide a sealing effect between the first andsecond chambers, two side surfaces of each of the intermeshing rotorsmust be engaged with the two inner surfaces of the casing respectivelysuch that the intermeshing rotors are engaged with the casing in asurface-to-surface contacting engagement to ensure the sealing effectbetween the first and second chambers. Otherwise, the mixture of liquidand air will leak to the second mixture through a clearance between theside surface of the intermeshing rotor and the inner surface of thecasing. In other words, if the intermeshing rotor is made of stainlesssteel, which is the same material of the casing, heat will besubstantially generated by the friction between the side surface of theintermeshing rotor and the inner surface of the casing when theintermeshing rotor is rotated. The heat will affect the quality of theice-cream or yogurt.

In other words, the intermeshing rotors must be made of differentmaterials such as alloy. When the teeth of the intermeshing rotors aremeshed with each other to transmit the rotational power from one toanother, the teeth of the intermeshing rotors are gradually torn,especially the teeth being precisely meshed. It is known that thedurability of stainless steel is better than that of alloy. When theintermeshing rotors are made of stainless, the service life span of theintermeshing rotors will be substantially prolonged. However, it isimpossible to incorporate the stainless steel made intermeshing rotorswith stainless steel casing because of the extreme high heat generationas it is mentioned above.

Furthermore, the torn intermeshing rotors must be replaced every threemonths when the intermeshing rotors are made of alloy. Most importantly,the alloy residues of torn intermeshing rotors will mix with theice-cream or yogurt through the suction effect of the pump from thefirst chamber to the second chamber. Therefore, the conventional pumpfor feeding liquid mixture for ice-cream or yogurt requires relativelyhigh maintenance cost and creates harmful substance to our health.

Accordingly, the liquid mixture is continuously pumped into casing tomake mixture product no matter the mixture product is dispensed out thecasing. In other words, the pump will continuously activate to make themixture product at any time to ensure the quality of the mixtureproduct. Once the pump is deactivated to stop pumping the liquid mixtureinto the casing, the mixture product left in the casing will melt. It isa waste when the mixture product is not required for being made. As aresult, the mixture product in the casing will be forced out through anoverflow aperture at the casing. Furthermore, the continuously runningthe pump will shorten the life span thereof.

SUMMARY OF THE PRESENT INVENTION

The invention is advantageous in that it provides a pump device for afrozen product machine, especially for a milk-frozen product such asyogurt or ice-cream machine, which can maintain the quality of theproduct at the time when it is dispensed.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein the run time of the pump device can bereduced from 80 to 95% comparing to the conventional pump device, so asto prolong the service life span of the pump device.

Another advantage of the invention is to provide a pump device for afrozen product machine, which can prevent the overflow of the pumpdevice.

Another advantage of the invention is to provide a pump device for afrozen product machine, which is capable of preventing mixture leakagewhile allowing convenient cleaning of the pump device.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein the sealing arrangement is providedbetween two outer side surfaces of the rotor gears and two inner sidesurfaces of the pump casing. Therefore, the sealing arrangement not onlyprovides a sealing effect for ensuring the liquid mixture and air beingsealed and mixed within the pumping cavity through the rotor gears butalso forms a partition for preventing the rotor gears from beingdirect-surface contact of the pump casing.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein no substantial heat is generated due tothe friction between the rotor gears and the pump casing.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein the rotor gears and said pump casing aremade of stainless steel to enhance the durability of the pump device soas to enhance the service life span thereof and to minimize any unwantedresidue being formed when the rotor gears are gradually worn.

Another advantage of the invention is to provide a pump device for afrozen product machine, which facilitates easy and convenient assemblingor disassembling of the pump casing.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein the components of the pump device can bemade with less precision without jeopardizing the overall quality of theice-cream or yogurt as compared to conventional pump devices. In otherwords, the manufacturing cost of the present invention can be minimizedwithout affecting its performance.

Another advantage of the invention is to provide a pump device for afrozen product machine, which does not involve complicated or expensivemechanical components so as to minimize the manufacturing cost of thepresent invention.

Another advantage of the invention is to provide a pump device for afrozen product machine, wherein no expensive or complicate mechanicalstructure is required to employ in the present invention in order toachieve the above mentioned objects. Therefore, the present inventionsuccessfully provides an economic and efficient solution for providing asealing effect within the pumping cavity for preventing direct surfacecontact between the rotor gears and the pump casing.

Additional advantages and features of the invention will become apparentfrom the description which follows, and may be realized by means of theinstrumentalities and combinations particular point out in the appendedclaims.

According to the present invention, the foregoing and other objects andadvantages are attained by providing a pump device for a frozen productmachine, which comprises a pump casing, a plurality of rotor gears, anda sealing arrangement.

The pump casing has two inner side surfaces, a pumping cavity betweenthe two inner side surfaces, a liquid inlet communicating the pumpingcavity with an exterior of the pump device for allowing liquid mixtureto be pumped into the pumping cavity through the liquid inlet, an airinlet communicating the pumping cavity for allowing intake of airthrough the air inlet to mix with the liquid mixture in the pumpingcavity, and a mixture outlet communicated with the frozen productmachine.

The rotor gears are fitted in the pumping cavity in a rotatably movablemanner, wherein the rotor gears are driven to rotate to create a suctioneffect for pumping and mixing the liquid mixture with the air from theliquid inlet and the air inlet respectively to the mixture outlet so asto produce a mixture product.

The sealing arrangement comprises a plurality of sealing elementsprovided between two outer side surfaces of the rotor gears and theinner side surfaces of the pump casing for ensuring the liquid mixtureand the air being sealed and mixed within the pumping cavity through therotor gears and for preventing the rotor gears from being direct-surfacecontact of the pump casing.

In accordance with another aspect of the invention, the presentinvention comprises a method of making frozen product, comprising thefollowing steps.

(1) Feed a liquid mixture and air into a pumping cavity of a pump casingthrough a liquid inlet and an air inlet thereof respectively.

(2) Drive two gear rotors to rotate within the pump casing forgenerating a suction effect to pump and mix the liquid mixture with theair to form a mixture product.

(3) Provide a sealing effect between two outer side surfaces of therotor gears and two inner side surfaces of the pump casing by a sealingarrangement for ensuring the liquid mixture and the air being sealed andmixed within the pumping cavity through the rotor gears and forpreventing the rotor gears from being direct-surface contact of the pumpcasing.

(4) Pump out the mixture product out of the pumping cavity through amixture outlet of the pump casing.

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ice-cream or yogurt machine with apump device according to a preferred embodiment of the presentinvention.

FIG. 2 is a perspective view of the pump device for an ice-cream oryogurt machine according to the above preferred embodiment of thepresent invention.

FIG. 3 is an exploded perspective view of the pump device for anice-cream or yogurt machine according to the above preferred embodimentof the present invention.

FIG. 4 is a side sectional view of the pump device for an ice-cream oryogurt machine according to the above preferred embodiment of thepresent invention.

FIG. 5 is a top sectional view of the pump device for an ice-cream oryogurt machine according to the above preferred embodiment of thepresent invention.

FIG. 6 illustrates a modification of a system of an ice-cream or yogurtmachine according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 to FIG. 5 of the drawings, a pump device for afrozen product machine 80, such as a yogurt machine or an ice-creammachine, according to a preferred embodiment of the present invention isillustrated, in which the pump device is embodied as a gear pump for thefeeding and mixing of liquid and air for the formation of liquid and airemulsions as a mixture product. Accordingly, the pump device of thepresent invention comprises a pump casing 10, a plurality of rotor gears20, 30, and a sealing arrangement 40.

The pump casing 10 has two inner side surfaces 101 and a pumping cavity16 defined between the two inner side surfaces 101. The pump casing 10further has a liquid inlet 13 communicating the pumping cavity 16, anair inlet 14 communicating the pumping cavity 16, and a mixture outlet15 communicating the pumping cavity 16 with the frozen product machine80.

According to the preferred embodiment, the pump device is embodied as atwo-gear pump to define first and second rotor gears 20, 30 fitted inthe pumping cavity 16 of the pump casing 10 in a rotatably movablemanner, wherein the first and second rotor gears 20, 30 are driven torotated to create a suction effect for pumping the mixing the liquidmixture with the air from the liquid inlet 13 and the air inlet 14respectively to the mixture outlet 15 so as to produce the frozenproduct.

The sealing arrangement 40 comprises a plurality of sealing elements 41provided between two outer side surfaces of the first and second rotorgears 20, 30 and the inner side surfaces 101 of the pump casing 10 forensuring the liquid mixture and the air being sealed and mixed withinthe pumping cavity 16 through the first and second rotor gears 20, 30and for preventing the first and second rotor gears 20, 30 from beingdirect-surface contact of the pump casing 10.

According to the preferred embodiment of the present invention, the pumpdevice is for pumping raw material for yogurt or ice-cream in liquidform, mix it with air and deliver it to the yogurt or ice-cream device.The pump is therefore connected between a storage tank 70 and the yogurtor ice-cream machine 80.

Accordingly, the liquid mixture is fed into the pumping cavity 16through the liquid inlet 13, wherein the liquid inlet 13 is formed atthe pump casing 10 as a through communication channel communicating thepumping cavity 16 with an exterior of the pump device for allowing theliquid mixture to be pumped into the pumping cavity 16 through theliquid inlet 13. In other words, the liquid inlet 13 communicates thepumping cavity 16 with an exterior of the pump device for allowingliquid mixture, such as raw materials for making the yogurt orice-cream, to be pumped from the storage tank 70 into the pumping cavity16 through the liquid inlet 13.

The air inlet 14 is formed at the pump casing 10 for allowing intake ofair through the air inlet 14 to mix with the liquid mixture in thepumping cavity 16. Once the liquid mixture is mixed with the air withinthe pumping cavity 16, the mixture product is produced and is deliveredout of the pumping cavity 16 through the mixture outlet 15 to the frozenproduct machine 80 for whipping process.

According to the preferred embodiment, the pump casing 10 comprises afirst casing member 11, a second casing member 12 detachably coupledwith the first casing member 11 to form the pumping cavity 16 within thefirst and second casing members 11, 12. Accordingly, the two inner sidesurfaces 101 of the pump casing 10 form at the first and second casingmembers 11, 12 respectively.

The pump casing 10 further comprises a plurality of fastening assemblies17 operatively provided on the pump casing 10 for selectively fasteningthe first and second casing member 11, 12. As shown in FIG. 3 of thedrawings, each of the fastening assemblies 17 contains a plurality offastening holes 171 spacedly formed at the second casing member 12, aplurality of elongated threaded heads 173 spacedly extended from thefirst casing member 11 to alignedly extend through the fastening holes171 respectively, and a plurality of threaded fastening knobs 172operatively fastened to the threaded heads 173 after the threaded heads173 extended through the fastening holes 171 for detachably fasteningthe corresponding portions of the first and the second casing member 11,12. Note that the fastening assemblies 17 are provided at two sideportions of the first and the second casing member 11, 12 so that eachfastening assembly 17 is arranged to fasten the correspond side portionsof the first and the second casing member 11, 12.

As shown in FIG. 5, the liquid inlet 13 is formed at bottom side of thepump casing 10. Preferably, the liquid inlet 13 is formed at the secondcasing member 12 of the pump casing 10. The liquid inlet 13 is connectedto the storage tank 70 via a feeding tube 71, wherein the liquid mixturefor making the ice-cream or yogurt is pumped into the pumping cavity 16via the feeding tube 71 and the liquid inlet 13.

As shown in FIG. 3, the feeding tube 71 has a feeding end rotatablycoupled at the liquid inlet 13, wherein a plurality of feeding holes 711are spacedly formed at the feeding end of the feeding tube 71. Thefeeding holes 711 are formed with different diameters for selectivelycontrolling the amount of the liquid mixture being fed into the pumpingcavity 16, such that when the feeding tube 71 is adjustably rotated at aposition that the pumping cavity 16 is alignedly communicated with oneof the feeding holes 711, the liquid mixture is fed into the pumpingcavity 16 via the corresponding feeding holes 711.

The air inlet 14 is formed at the front side of the pump casing 10 at abottom portion thereof. Preferably, the air inlet 14 is formed at thesecond casing member 12 of the pump casing 10.

The mixture outlet 15 is formed at the front side of the pump casing 10at an upper portion thereof. Preferably, the mixture outlet 15 is formedat the second casing member 12 of the pump casing 10.

The first and the second rotor gears 20, 30 are rotatably received inthe pumping cavity 16 for creating a vacuum effect to suck liquidmixture and air through the liquid inlet 13 and the air inlet 14 intothe pumping cavity 16. The first and the rotor gears 20, 30 also deliverpumping force to pump the mixture of the liquid mixture and the air outof the pumping cavity 16 through the mixture outlet 15.

Moreover, the pump casing 10 is communicated with a motor device 60which is arranged to drive the rotor gears 20, 30 to rotate for suckingthe liquid raw material and air into the pumping cavity 16, and creatinga pumping force, i.e. the suction effect, to deliver the mixture productto the frozen product machine 80 for making the frozen product such asyogurt or ice-cream.

More specifically, the first rotor gear 20 has two outer side surfaces201 and an outer circumferential edge portion between the two outer sidesurfaces 201. The first rotor gear 20 further comprises a plurality offirst engaging teeth 21 peripherally formed along the outercircumferential edge portion of the first rotor gear 20.

The second rotor gear 30 has two outer side surfaces 301 and an outercircumferential edge portion between the two outer side surfaces 301.The second rotor gear 30 further comprises a plurality of secondengaging teeth 31 peripherally formed along the outer circumferentialedge portion of the second rotor gear 30, wherein the first engagingteeth 21 are meshed with the second engaging teeth 31 such that when thefirst gear rotor 20 is rotated, the second gear rotor 30 is driven torotate. In other words, the first rotor gear 20 is the driving gearwhile the second rotor gear 30 is the driven gear. Thus, the first rotorgear 20 is connected to the motor device 60 which drives the first rotorgear 20 to rotate at a predetermined speed.

Thus, the pumping casing 10 further has a driving slot 18 formed on thefirst casing member 11, whereas the motor device 60 comprises a drivingshaft 61 extended to connect with the first gear rotor 20 via thedriving slot 18 so as to drive the first gear rotor 20 to rotate at apredetermined speed.

Thus, the first rotor gear 20 further has a first gear slot 22 formed ata mid-potion thereof, wherein the driving shaft 61 of the motor device60 is arranged to connect to the first gear slot 22 through the drivingslot 18 for driving the first rotor gear 20 to rotate. On the otherhand, the second rotor gear 30 further has a second gear slot 32 whereasthe pump casing 10 further comprises a supporting shaft 19 extended fromthe first casing member 11 to connect with the second gear slot 32,wherein the second rotor gear 30 is arranged to be driven to rotate bythe first rotor gear 20 about the supporting shaft 19. The second rotorgear 30 further comprises an intermediate member 33 provided between thesupporting shaft 19 and the outer circumferential edge portion 301 ofthe second rotor gear 30.

As shown in FIG. 5, the first rotor gear 20 are meshed with the secondrotor gear 30 to define a first chamber 161 within the pumping cavity 16to communicate with the liquid inlet 13 and a second chamber 162 withinthe pumping cavity 16 to communicate with the mixture outlet 15, whereinthe pumping cavity 16 is sealed by the sealing arrangement 40 forensuring the liquid mixture and air being mixed from the first chamber161 to the second chamber 162 to form the mixture product.

Accordingly, when the first and second rotor gears 20, 30 are driven torotate, the suction effect is created to feed the liquid mixture and airfrom the first chamber 161 to the second chamber 162. Therefore, thefirst and second chambers 161, 162 must be sealed tightly to ensure theleakage of the liquid mixture and air.

On the other hand, the pump casing 10 preferably has two air inlets 14spacedly formed on the second casing member 12, wherein a predeterminedamount of air is sucked into the pumping cavity 16 via the two airinlets 14 for mixing with the liquid mixture to form the mixture productwhich is to be delivered to the yogurt or ice-cream machine 80 throughthe mixture outlet 15.

Accordingly, the two air inlets 14 are formed at the bottom portion ofthe pump casing 10 to align with two bottom portions of the first andsecond gear rotors 20, 30 respectively, wherein the air is filled at thegaps between the engaging teeth 21, 31 of the first and second gearrotors 20, 30 such that the air will be delivered into the first chamber161 during the rotational movements of the first and second gear rotors20, 30.

As a result, the mixture outlet 15 is also formed on the second casingmember 12 in such a manner that the mixture of liquid and air is to bedelivered out of the pumping cavity 16 via the mixture outlet 15. Adischarge tube 50 is connected between the mixture outlet 15 and theyogurt or ice-cream machine 80 for transporting the mixture from thepumping cavity 16 to the yogurt or ice-cream machine 80.

As it is mentioned above, the conventional design of the pump device isthat the outer side surface 201, 301 of each of the first and secondrotor gears 20, 30 must be tightly engaged with the corresponding innerside surface 101 of the pump casing 10 to prevent the leakage of theliquid mixture and air through the clearance between the outer sidesurfaces 201, 301 of the first and second rotor gears 20, 30 and theinner side surface 101 of the pump casing 10.

According to the preferred embodiment, the sealing arrangement 40 isprovided at the clearance between the outer side surfaces 201, 301 ofthe first and second rotor gears 20, 30 and the inner side surface 101of the pump casing 10. Therefore, the outer side surfaces 201, 301 ofthe first and second rotor gears 20, 30 will not contact with the innerside surface 101 of the pump casing 10 while sealing effect is providedat the clearance.

As shown in FIGS. 3 and 4, each of the sealing elements 41 is made ofelastic material adapted to be deformed to fit between the outer sidesurface 201, 301 of each of the first and second rotor gears 20, 30 andthe corresponding inner side surface 101 of the pump casing 10 so as tocreate the sealing effect therebetween while enabling each of the rotorgears 20, 30 being rotated within the pumping cavity 16.

Preferably, each of the sealing elements 41 is made of rubber materialwhich is capable of preventing air and liquid from passing through thearea sealed by the corresponding sealing elements 41.

As shown in FIGS. 3 and 4, each of the sealing elements 41 is embodiedas a sealing ring retained at the outer side surface 201, 301 of each ofthe first and second rotor gears 20, 30 to bias against thecorresponding inner side surface 101 of the pump casing 10. Therefore,the liquid mixture and air must pass from the first chamber 161 to thesecond chamber 162 through the meshing engagement between the first andsecond engaging teeth 21, 31 during the rotational movements of thefirst and second gear motors 20, 30. It is worth mentioning that thesealing elements 41 provide substantially complete sealing of the liquidmixture and the air so as to allow effective mixture of the air and theliquid within the pumping cavity 16 while facilitating easy andconvenient disassembling and reassembling of the pump casing 10.

Thus, the sealing elements 41 are provided at the first and the secondrotor gears 20, 30 respectively for preventing the air and the liquidsucked by the first and the second rotor gears 20, 30 from reaching thearea sealed by the sealing elements 41 within the pumping cavity 16(i.e. the central portion of each of the first and the second rotor gear20, 30).

The sealing arrangement 40 further comprises a plurality of sealingslots 42 indent on the outer side surfaces 201, 301 of the first andsecond gear rotors 20, 30 respectively, wherein the sealing elements 41are retained at the sealing slots 42 respectively to contact and sealwith the inner side surfaces 101 of the pump casing 10.

Each of the sealing slots 42 is shaped corresponding to the respectivesealing element 41, wherein when the sealing element 41 is disposed atthe sealing slot 42, a portion of the sealing element 41 is received inthe sealing slot 42 to retain the sealing element 41 in position whileanother portion of the sealing element 41 is protruded out of the outerside surfaces 201, 301 of the respective first and second gear rotors20, 30 so as to bias against the respective inner side surface 101 ofthe pump casing 10.

Accordingly, each of the sealing elements 41 is embodied as asubstantially circular sealing ring received in the sealing slots 42.Accordingly, each of the sealing slots 42 is also substantially circularin cross section which is arranged to fittedly accommodate thecorresponding sealing element 41. Note that the sealing slot 42 at thesecond rotor gear 30 is formed at the boundary between the intermediatemember 33 and the outer circumferential edge portion of the second rotorgear 30.

Since the sealing elements 41 are pressed between the outer side surface201, 301 of each of the first and second rotor gears 20, 30 and thecorresponding inner side surface 101 of the pump casing 10, the firstand second rotor gears 20, 30 will not directly contact with the pumpcasing 10 in a surface-to-surface contacting manner. Therefore, therewill be no heat generation by the friction between the outer sidesurfaces 201, 301 of the first and second rotor gears 20, 30 and theinner side surfaces 101 of the pump casing 10 during the rotationalmovements of the first and second gear motors 20, 30.

After solving the unwanted heat generated problem, all the pump casing10, and the first and second rotor gears 20, 30 can be made of stainlesssteel. When both the first and second rotor gears 20, 30 are made ofstainless steel, the durability of the first and second engaging teeth21, 31 will be substantially enhanced to prolong the service life spanof the first and second rotor gears 20, 30. As it is mentioned above, ifthe first and second rotor gears 20, 30 are made of alloy, they must befrequently replaced for every three months. When the first and secondrotor gears 20, 30 are made of stainless steel, they can be frequentlyreplaced for every three years. Accordingly, there will be no orrelatively less amount of residues formed during the rotationalmovements of the first and second gear motors 20, 30, wherein suchamount of residues is under the safety level.

It is worth mentioning that since the pump device is substantiallysealed by the sealing arrangement 40, the engagement between the firstand the second rotor gears 20, 30 can be made less precise as comparedto conventional pumping devices. This eventually reduces themanufacturing cost and the ultimate selling price of the presentinvention.

The sealing arrangement 40 further comprises a casing sealing element 43provided between the first and second casing members 11, 12 to seal thepumping cavity 16 within the first and second casing members 12, 12 whenthe first and second casing members 11, 12 are coupled together.

The sealing arrangement 40 further has a retention slot 44 indent at theperipheral portion of the first casing member 11 to retain the casingsealing element 43 thereat so as to bias against the second casingmember 12 when the first and second casing members 11, 12 are coupledtogether.

Likewise, the casing sealing element 43 is made of rubber material whichis capable of preventing air and liquid from passing through the areasealed by the casing sealing element 43. Accordingly, the casing sealingelement 43 is arranged to encircle a peripheral edge portion of thefirst and the second casing member 11, 12. Thus, the retention slot 44is indently formed on the first casing member 11 at a positionencircling a peripheral side edge portion thereof so as to prevent airand liquid leakage from the pumping cavity 16. When the pumping cavity16 is sealed from ambient atmosphere, the efficiently of the pump deviceof the present invention can be substantially enhanced because thepumping action of the pump device is accomplished by rotation of thefirst and the second rotor gear 20, 30, which creates a vacuum effect inthe pumping cavity 16 for sucking liquid from the storage tank 70 andthe air from the surrounding environment.

The operation of the present invention is as follows: a user of thepresent invention will first put raw materials in liquid form into thestorage tank 70. When the motor device 60 is operated, the first and thesecond rotor gears 20, 30 will be driven to rotate for creating a vacuumeffect in the pumping cavity 16. As a result, the raw materials storedin the storage tank 70 will then be sucked into the pumping cavity 16through the liquid inlet 13. Air will also be sucked into the pumpingcavity 16 through the air inlet 14. The air will then mix with the rawmaterials in liquid form to become the mixture product, which isdischarged through the mixture outlet 15 of the pump casing 10. Thesealing arrangement 40 ensures substantial sealing of the pumping cavity16 which reduces the manufacturing cost of other components of the pumpdevice and provide efficient and effective vacuum of the pumping cavity16.

As shown in FIG. 6, a modification of a system of an ice-cream or yogurtmachine according to a second embodiment of the present invention isillustrated, wherein the system further comprises a casing 10A and aclutch unit 20A operatively linked between the pump device and thecasing 10A.

The casing 10A has a concealed cavity 11A, an inlet 12A for allowing themixture product to be input into the concealed cavity 11A via the pumpdevice, and an outlet 13A for dispensing the mixture product from theconcealed cavity 11A. The casing 10A is made of heat-insulated materialto maintain the temperature of the mixture product within the concealedcavity 11A. Accordingly, the interior pressure of the concealed cavity11A is defined when the outlet 13A is closed.

The clutch unit 20A is operatively linked to the pump device forcontrollably maintaining the interior pressure of the concealed cavity11A at a predetermined threshold. In particular, the pump device isactivated by the clutch unit 20A for delivering the mixture product intothe concealed cavity 11A through the inlet 12A until the interiorpressure of the concealed cavity 11A reaches the predeterminedthreshold. The pump device is also deactivated by the clutch unit 20Afor stop delivering the mixture product into the concealed cavity 11Awhen the interior pressure of the concealed cavity 11A reaches thepredetermined threshold. Accordingly, the clutch unit 20A is operativelylinked to the motor device 60 of the pump device, such that the motordevice 60 is controllably activated by the clutch unit 20A. Therefore,the run time of the pump device will be minimized that the pump devicewill be activated only in response to the interior pressure of theconcealed cavity 11A.

Accordingly, when the mixture product is fed into the concealed cavity11A of the casing 10A, the interior pressure of the concealed cavity 11Awill be increased. It is worth mentioning that the pump device isactivated to feed the mixture product into the concealed cavity 11Awhile the outlet 13A of the casing 10A is closed. Once the interiorpressure of the concealed cavity 11A reaches the predeterminedthreshold, the pump device is deactivated, such that no mixture productwill be fed into the concealed cavity 11A. When the interior pressure ofthe concealed cavity 11A reaches the predetermined threshold, theinterior pressure of the concealed cavity 11A will be higher than anexterior pressure of the concealed cavity 11A.

In order to reduce the interior pressure of the concealed cavity 11A,the outlet 13A of the casing 10A is opened to dispense the mixtureproduct therein. Accordingly, the pump device is activated/re-activatedby the clutch unit 20A when the outlet 21A of the casing 10A is openedto reduce the interior pressure of the concealed cavity 11A below thepredetermined threshold. It is worth mentioning that the clutch unit 20Ais arranged to maintain the interior pressure of the concealed cavity11A at the predetermined threshold. Therefore, when the interiorpressure of the concealed cavity 11A drops below the predeterminedthreshold, the pump device is activated. Likewise, when the interiorpressure of the concealed cavity 11A reaches the predeterminedthreshold, the pump device is deactivated. As a result, the pump devicewill not be operated all the time.

As shown in FIG. 6, the casing 10A further comprises a stirring unit 14Aoperatively supported in the concealed cavity 11A for stirring themixture product within the concealed cavity 11A. Accordingly, thestirring unit 14A comprises a longitudinal propeller coaxially androtatably supported within the concealed cavity 11A for delivering andstirring the mixture product from the inlet 12A to the outlet 13A of thecasing 10A in a spirally delivering manner. Accordingly, the stirringunit 14A can be operatively linked to the frozen product machine 80.

As shown in FIG. 6, the clutch unit 20A comprises a one-way check valve21A having a valve inlet 211A operatively linked to the mixture outlet15 of the pump casing 10 of the pump device and a valve outlet 212Aoperatively linked to the inlet 12A of the casing 10A. Therefore, themixture product will be delivered to the concealed cavity 11A from thepump device through the one-way check valve 21A. However, the mixtureproduct cannot be returned back to the pump device from the concealedcavity 11A.

Accordingly, when the outlet 13A of the casing 10A is closed and thepump device is activated, the one-way check valve 21A is opened forletting the mixture product to deliver to the concealed cavity 11A. Whenthe outlet 13A of the casing 10A is closed and the pump device isdeactivated, the one-way check valve 21A is closed to maintain theinterior pressure of the concealed cavity 11A at the predeterminedthreshold.

The one-way check valve 21A is closed by the pressure difference of thecasing 10A. The one-way check valve 21A is closed when the interiorpressure of the concealed cavity 11A is higher than an exterior pressureof the concealed cavity 11A.

Alternatively, the clutch unit 20A comprises a timer switch 22Aoperatively linked to the pump device, wherein the timer switch 22A isarranged to activate the pump device after the outlet 13A of the casing10A is opened for a predetermined opening time. In other words, once theoutlet 13A of the casing 10A is opened for dispensing the mixtureproduct for a predetermined opening time, the pump device will beactivated by the timer switch 22A. It is worth mentioning that thedispensing rate of the mixture product at the outlet 13A of the casing10A is known. Once the outlet 13A of the casing 10A is opened, themixture product will be dispensed from the concealed cavity 11A until itis empty. Before emptying the concealed cavity 11A, the pump device willbe activated by the timer switch 22A to feed the mixture product intothe concealed cavity 11A. For example, the opening time of the outlet13A is set as five seconds. Therefore, after the outlet 13A is openedfor five seconds to dispense the mixture product, i.e. reducing theinterior pressure of the concealed cavity 11A, the pump device will beactivated by the timer switch 22A.

Furthermore, the feeding rate of the mixture product of the pump deviceto feed the mixture product to the casing 10A is known. Therefore, thetimer switch 22A will deactivate the pump device after a predeterminedactivating time of the pump device. For example, after the pump deviceis activated for one minute to feed the mixture product into theconcealed cavity 11A, i.e. increasing the interior pressure thereof, thepump device will be deactivated by the timer switch 22A after one minuteof activating time.

According to the preferred embodiment, the pump device will be activatedonly when the interior pressure of the casing 10A is below thepredetermined threshold. Therefore, the pump device will be stopped topump out the mixture product so as to prevent the overflow of the pumpdevice. Furthermore, the mixture product is stored and concealed in theconcealed cavity 11A under a higher pressure with respect to theexterior pressure of the casing 10A. The quality of the mixture productwill be maintained as the mixture product freshly made at the pumpdevice once the liquid mixture is freshly mixed with the air. The systemof the present invention is an environmentally friendly product that thepump device will be activated only as necessary while being energyefficient.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting. It will thus be seenthat the objects of the present invention have been fully andeffectively accomplished. It embodiments have been shown and describedfor the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A system for a frozen product machine,comprising: a pump device for mixing liquid mixture with air to producea mixture product; a casing having a concealed cavity, an inlet forallowing said mixture product to be input into said concealed cavity viasaid pump device, and an outlet for dispensing said mixture product fromsaid concealed cavity; and a clutch unit operatively linked to said pumpdevice for controllably maintaining an interior pressure of saidconcealed cavity at a predetermined threshold, wherein said pump deviceis activated by said clutch unit for delivering said mixture productinto said concealed cavity through said inlet until said interiorpressure of said concealed cavity reaches said predetermined thresholdand is deactivated by said clutch unit for stop delivering said mixtureproduct into said concealed cavity when said interior pressure of saidconcealed cavity reaches said predetermined threshold.
 2. The system, asrecited in claim 1, wherein said pump device is activated by said clutchunit when said outlet of said casing is opened to reduce said interiorpressure of said concealed cavity below said predetermined threshold. 3.The system, as recited in claim 1, wherein said clutch unit comprises aone-way check valve having a valve inlet operatively linked to a mixtureoutlet of said pump device and a valve outlet operatively linked to saidinlet of said casing, wherein when said outlet of said casing is closedand said pump device is activated, said one-way check valve is openedfor letting said mixture product to deliver to said concealed cavity,wherein when said outlet of said casing is closed and said pump deviceis deactivated, said one-way check valve is closed to maintain saidinterior pressure of said concealed cavity at said predeterminedthreshold.
 4. The system, as recited in claim 2, wherein said clutchunit comprises a one-way check valve having a valve inlet operativelylinked to a mixture outlet of said pump device and a valve outletoperatively linked to said inlet of said casing, wherein when saidoutlet of said casing is closed and said pump device is activated, saidone-way check valve is opened for letting said mixture product todeliver to said concealed cavity, wherein when said outlet of saidcasing is closed and said pump device is deactivated, said one-way checkvalve is closed to maintain said interior pressure of said concealedcavity at said predetermined threshold.
 5. The system, as recited inclaim 1, wherein said casing further comprises said stirring unitoperatively supported in said concealed cavity for stirring said mixtureproduct within said concealed cavity.
 6. The system, as recited in claim2, wherein said casing further comprises said stirring unit operativelysupported in said concealed cavity for stirring said mixture productwithin said concealed cavity.
 7. The system, as recited in claim 4,further comprising said stirring unit operatively supported in saidconcealed cavity for stirring said mixture product within said concealedcavity.
 8. The system, as recited in claim 5, wherein said pump devicecomprises a motor device operatively linked to clutch unit.
 9. Thesystem, as recited in claim 1, wherein said pump device comprises amotor device operatively linked to clutch unit.
 10. The system, asrecited in claim 7, wherein said pump device comprises a motor deviceoperatively linked to clutch unit.
 11. A method of making frozenproduct, comprising the steps of: (a) activating a pump device by aclutch unit for delivering a mixture product into a concealed cavity ofa casing through an inlet thereof, so as to increase an interiorpressure of said concealed cavity; and (b) deactivating said pump deviceby said clutch for stop delivering said mixture product into saidconcealed cavity when said interior pressure of said concealed cavityreaches a predetermined threshold so as to controllably maintain saidinterior pressure of said concealed cavity at said predeterminedthreshold.
 12. The method, as recited in claim 11, further comprising astep of operatively linking a valve inlet and a valve outlet of aone-check valve at mixture outlet of said pump device and said inlet ofsaid casing respectively.
 13. The method, as recited in claim 12,wherein said one-check valve is operated by the steps of: opening saidone-way check valve letting said mixture product to deliver to saidconcealed cavity when said outlet of said casing is closed and said pumpdevice is activated; and closing said one-way check valve to maintainsaid interior pressure of said concealed cavity at said predeterminedthreshold when said outlet of said casing is closed and said pump deviceis deactivated.
 14. The method, as recited in claim 11, furthercomprising a step of re-activating said pump device by said clutch unitfor pumping said liquid mixture into said concealed cavity when anoutlet of said casing is opened to release said mixture product fromsaid concealed cavity and to reduce said interior pressure of saidconcealed cavity below said predetermined threshold.
 15. The method, asrecited in claim 12, further comprising a step of re-activating saidpump device by said clutch unit for pumping said liquid mixture intosaid concealed cavity when an outlet of said casing is opened to releasesaid mixture product from said concealed cavity and to reduce saidinterior pressure of said concealed cavity below said predeterminedthreshold.
 16. The method, as recited in claim 13, further comprising astep of re-activating said pump device by said clutch unit for pumpingsaid liquid mixture into said concealed cavity when an outlet of saidcasing is opened to release said mixture product from said concealedcavity and to reduce said interior pressure of said concealed cavitybelow said predetermined threshold.
 17. The method, as recited in claim11, further comprising a step of stirring said mixture product withinsaid concealed cavity via a stirring unit.
 18. The method, as recited inclaim 16, further comprising a step of stirring said mixture productwithin said concealed cavity via a stirring unit.
 19. The method, asrecited in claim 11, wherein said clutch unit is operatively linked to amotor device of said pump device.
 20. The method, as recited in claim18, wherein said clutch unit is operatively linked to a motor device ofsaid pump device.